The regulator said it received 1,453 complaints in 2008, compared with 577 in 2007. The advert that generated the most complaints was by children's charity Barnado's, which showed repeated footage of a man hitting his daughter and provoked more than half the 2008 complaints (Third Sector Online, 4 December).

The rise in the number of complaints prompted the regulator to issue a report warning that charities are subject to the same rules as other sectors, even if they do have more reasons to use hard-hitting tactics.

The report says that "it is not the ASA's intention to act as a censor" and that "judging what is and is not offensive is a subjective matter that can be difficult for the ASA to adjudicate on - particularly if the ad is in support of a good cause".

The ASA said that charities and campaigning groups were more likely than others to overstep the mark because of the often urgent nature of their causes. "Shock tactics can be effective at raising awareness of important issues, but this does not give charities carte blanche to risk causing serious public offence or distress," an ASA spokesman said.